In vitro diagnostic assays are a burgeoning, increasingly sophisticated, field in the health care industry. Many such assays rely on affinity or capture probe deposition to a solid support, followed by incubation with a sample suspected of containing an analyte of interest that specifically binds to the capture probe.
The binding event is then signaled through use of a label of some sort, e.g., colorimetric, radioactive, or electronic. The label can be covalently or noncovalently bound directly or indirectly to a binding pair complement probe, e.g., a capture probe (or, in sandwich assay configurations, a signal probe). In some assays configurations, it can also be attached to analyte before binding to a capture probe, e.g., as in label incorporated into PCR amplified nucleic acid analyte. In electrochemical detection schemes the probe or signal can also be based on the establishment and subsequent perturbation of an electronic property, such as a field or charge potential or current, e.g., as occur in various field effect transistor (FET)-based, surface plasmon-resonance (SPR)-based, and redox-based detection schemes. Electronic-based signaling schemes typically employ electrodes, and these and other signaling schemes are all well-known in the art.
Applicants' commercial eSensor® XT-8 system (GenMark Diagnostics, Inc.; Carlsbad, Calif., USA) is a redox-based electronic detection scheme that makes use of AC/DC voltammetry. Specific technology embodied in Applicants' system is described in detail in exclusively-licensed U.S. Pat. Nos. 6,258,545 and 6,071,699, commonly-owned U.S. Pat. Nos. 7,056,669, 6,740,518, 6,761,816, 7,534,331, 6,960,467, and 6,875,619, and commonly-owned PCTUS08/54136 (published as WO2008101196), the contents of each of which are herein incorporated by reference. Applicants currently offer a variety of multiplex human genotyping assays for use the eSensor® XT-8 system and are working to develop and commercialize multiplex infectious disease testing assays on the same platform.
Infectious disease testing by nature typically generates a much higher percentage of negative results. For a multiplex array-based electronic detection platform such as Applicants' eSensor® XT-8 system, this means that most detection electrodes return no signal in any given infectious disease panel test.
It has not heretofore been possible in Applicants' system to distinguish a non-signaling electrode caused by a true negative sample from a malfunctioning electrode resulting from compromised capture probe integrity or a manufacturing-related problem such as a failure to properly spot capture probe. Moreover, multiplex genotyping systems sometimes feature background signal or noise attributable to adjacent sequence variations that can occur concomitantly with a sequence or residue of interest to be interrogated.
The present invention, depending on aspect and embodiment, addresses either or both of these deficiencies.